Cowen, the investment banking subsidiary of France's Societe Generale, has joined the unbundling parade, TheStreet.com has learned.

In an amendment to its initial public offering filing, Cowen said it is a "party to two unbundling arrangements." Cowen didn't name the institutions, but the statement indicates the firm has become the latest on Wall Street to allow big customers to pay separately for research and trading.

Research and stock trading traditionally have been sold as a package on Wall Street. But investors and regulators have grown increasingly critical of the potential conflicts of interest in that arrangement.

Lehman Brothers

(LEH)

last October became the first big Wall Street firm to lay out unbundling plans, cutting a deal with

Fidelity

. Fidelity is the only institution that has disclosed its unbundling plans.

TheStreet.com

reported in January that Lehman's decision was paying early dividends, forcing rivals to play along.

In the filing, Cowen warns that the unbundling route is no walk in the park.

"We may enter into additional unbundling arrangements in the future," the May 17 filing says. But Cowen goes on to add in the risk factors section:

"If unbundling becomes prevalent, there can be no assurance that our sales and trading clients will also pay us separately for our research, or if they do, that our revenues from these clients will be the same as they are currently," Cowen's filing said. "If our clients wish to purchase sales and trading and research services separately, there can be no assurance that we will be able to market our services on that basis as effectively as some of our competitors, in which case our business could be adversely affected."

Lehman's pioneering unbundling deal gives Fidelity a flat fee for its research and a lower fee for trading execution.

Deutsche Bank

(DB) - Get Report

and

Thomas Weisel

(TWPG)

later said they had agreed to unbundling deals with Fidelity.

Cowen is the second boutique to cite unbundling as a potential risk to its business. Thomas Weisel also

said in its recent IPO filing that unbundling could "impair the revenues of our brokerage business."

Although Wall Street has been somewhat enamored of the unbundling trend, some executives have recently spoken candidly about the evolution of the trading business, and the reasons for Wall Street to cut such deals.

On a recent call with Prudential analyst Chris Spahr and a group of institutional investors,

Alliance Bernstein

(AB) - Get Report

chief Lewis Sanders said of the research vs. trading tug of war, "Our approach to the business, it is actually evolving."

"The bottom line from our point of view is

unbundling is a good thing," Sanders said. "Because what it really means is that value propositions that are well supported are more likely to win out. Any time there is increased exposure and scrutiny and attention, then I think it is a natural result that pricing will align itself with underlying value."